High-resolution image simulation of overlap structures in TiAl alloy

Chen, Chun Lin; Lü, Wei; Cui, Yue; He, L. L.; Ye, H. Q.

doi:10.1016/j.jallcom.2008.01.027

Cited by 15 publications

(8 citation statements)

References 39 publications

(49 reference statements)

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“…This corresponds to double diffraction phenomena and leads to the conclusion that the fringes observed are due to the superimposition of γ and δ phases. Such a superimposition and the associated fringes have been reported by Chen et al [22] in TiAl alloys where the phases involved were the L1 0 -gamma and DO 19 -alpha phases.…”

Section: Tem Observationsupporting

confidence: 77%

TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy

Dehmas

Lacaze

Niang

et al. 2011

Advances in Materials Science and Engineering

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Inconel 718 is widely used because of its ability to retain strength at up to 650∘C for long periods of time through coherent metastable Ni3Nb precipitation associated with a smaller volume fraction of Ni3Al precipitates. At very long ageing times at service temperature, decomposes to the stable Ni3Nb phase. This latter phase is also present above the solvus and is used for grain control during forging of alloy 718. While most works available on precipitation have been performed at temperatures below the solvus, it appeared of interest to also investigate the case where phase precipitates directly from the fcc matrix free of precipitates. This was studied by X-ray diffraction and transmission electron microscopy (TEM). TEM observations confirmed the presence of rotation-ordered domains in plates, and some unexpected contrast could be explained by double diffraction due to overlapping phases.

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Section: Tem Observationsupporting

confidence: 77%

TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy

Dehmas

Lacaze

Niang

et al. 2011

Advances in Materials Science and Engineering

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“…In the literature, in order to distinguish the true 9R structure from an overlapping region between twin and matrix grains, both occurring in twinned materials and both causing an extra threefold periodicity in the

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HRTEM images of an fcc lattice, the local diffraction patterns must be analyzed in detail . In the present work, both situations occur, as seen from the comparison in Fig.…”

Section: Resultsmentioning

confidence: 92%

“…One is the formation of a 9R structure with the emission of one stacking fault every three {111} planes in the fcc structure and the resulting stacking sequence of ABCBCACAB. The other possibility is the overlapping twin–matrix, which reveals an almost similar HRTEM contrast .…”

Section: Resultsmentioning

confidence: 98%

Review on TEM analysis of growth twins in nanocrystalline palladium thin films: Toward better understanding of twin-related mechanisms in high stacking fault energy metals

Idrissi

Amin-Ahmadi

Wang

et al. 2014

Phys. Status Solidi B

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Various modes of transmission electron microscopy including aberration corrected imaging were used in order to unravel the fundamental mechanisms controlling the formation of growth twins and the evolution of twin boundaries under mechanical and hydrogen loading modes in nanocrystalline (nc) palladium thin films. The latter were produced by electron‐beam evaporation and sputter deposition and subjected to uniaxial tensile deformation as well as hydriding/dehydriding cycles. The results show that the twins form by dissociation of grain boundaries. The coherency of Σ3{111} coherent twin boundaries considerably decreases with deformation due to dislocation/twin boundary interactions while Σ3{112} incoherent twin boundaries dissociate under hydrogen cycling into two‐phase boundaries bounding a new and unstable 9R phase. The effect of these elementary mechanisms on the macroscopic behavior of the palladium films is discussed and compared to recent experimental and simulation works in the literature. The results provide insightful information to guide the production of well‐controlled population of growth twins in high stacking fault energy nc metallic thin films. The results also indicate directions for further enhancement of the mechanical properties of palladium films as needed for instance in palladium‐based membranes in hydrogen applications.

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“…Both phenomena have been observed in many thin films [20][21][22]. High-resolution images showing a periodic contrast with three-layer (1 1 1) planes in TiAl alloys have been verified to result from the overlapped twins by the comparisons of experimental techniques and theoretic simulations [23]. A further work on distinguishing Moiré fringes from the second phase in the CZT thin films is still undergoing.…”

Section: Orientation Relationship and Twin Configurationsmentioning

confidence: 87%